Penn State study shows killer T cells critical to vaccines

Researchers from Penn State have discovered the human immune system needs enough killer T cells to respond to viral threats, which may be a critical component for more effective vaccines in the future.

The immune responses of mice showed that regulatory T cells, called Tregs, are crucial for the immune system’s memory, which is responsible for fighting off future attacks on the body. T cells are specialized white blood cells.

T cells that respond to the initial attack are called naïve T cells because they do not have any defenses or experience to fight the invasion. As the body creates more T cells, they become killer T cells and are more efficient in killing off the attack.

"Immunological memory is the capability of your immune system to remember the diseases and pathogens it fought off in the past, and the generation of long-lived immunological memory is the basis of effective vaccination," Surojit Sarkar, assistant professor of immunology in veterinary and biomedical sciences, said. "Once the T cells clear the pathogen, just like in warfare, you do not leave your weapons drawn, you holster them. In the case of the immune system, those charged killer T cells also downregulate their killer machinery."

Vandana Kalia, who worked with Sarkar on the study, compared
Tregs to the police of our immune system, saying their job is to keep other immune cells in check
said.

"In the case of memory T cells, Tregs serve to keep their killer functions in check and help maintain them in a quiescent, yet ready to kill, state," Kalia said. "What our study is doing is looking at the basic concepts of how the immune system's memory develops and such fundamental information is critical for advancing our current vaccine development efforts."

Sakar also noted that their study's findings are deeply rooted in a historic context.

"The Greek historian Thucydides observed that people who had been exposed to the plague once -- and survived it -- felt more comfortable helping other plague victims because they knew that they would not be attacked fatally again," he said.